Twitter has experienced a tremendous growth since its inception and is considered as an effective and simple social medium for communication. Despite its huge uptake, less is known about the usage of Twitter as a learning tool especially within higher education. This study investigates the adoption of Twitter in an e-Commerce unit in an Australian higher education institution. Building on Twitter's inherent social features, an extension to Davis's original Technology Acceptance Model (TAM) is devised by including intrinsic and extrinsic motivation behaviours as predictors of Twitter usage. The empirical evaluation does not provide support to the original TAM constructs of usefulness and ease-of-use but reveals enjoyment and social norms as the strongest predictors. The study implications suggest a mind-shift in the adoption of Web 2.0 tools as compared to that of traditional Web technologies, i.e., Web 2.0 is more about enjoyment and social presence and not merely about how useful or easy-to-use a technology is.